No-fuse circuit breaker

ABSTRACT

A no-fuse circuit breaker comprising at least one movable contact arm, one end portion of which is rotatably supported on a mechanism frame and the other end of which is provided with a contact point engagable with a stationary contact in the mechanism. An intermediate portion of the movable contact arm is operatively connected to one end of a pair of links operatively connected in series, the other end of the links being operatively connected to an operating handle rotatably mounted on the mechanism frame. A latching member is rotatably mounted on the mechanism frame, being engageable with one end of a releasable member, the other end of the releasable member being operatively connected to a knee connection between the pair of links, whereby the movement of the knee connection is restricted by the releasable member when latched by the latching member. Thus, the movable contact arm is actuated by the operating handle when the releasable member is latched by the latching member, and the movable contact arm can be tripped when the restriction in the movement of the knee connection of the links is released due to disengagement of the releasable member with the latching member as may be caused by the rotation thereof.

United States Patent 1 Sugiyama Nov. 20, 1973 NO-FUSE CIRCUIT BREAKER[75] Inventor: Sigeru Sugiyama, Tokyo, Japan [73] Assignee: TokyoShibaura Electric Company,

Kawasaki-shi, Japan 22 Filed: Nov. 9, 1972 21 Appl. No'.; 305,078

[30] Foreign Application Priority Data Dec. 1, 1971 Japan 46/112222 [52]US. Cl. 335/167, 335/172, 335/175, 335/191 [51] Int. Cl. H0lh 9/20 [58]Field of Search 335/174, 175, 35, 335/38, 221,167,168,l69,170,191,21,172

[56] References Cited UNITED STATES PATENTS 3,395,372 7/1968 Opad335/174 3,329,912 7/1967 Brackettn 335/175 Primary Examiner-HaroldBroome Attorney--Norman F. Oblon et al.

OFF

. [57] ABSTRACT A no-fuse circuit breaker comprising at least onemovable contact arm, one end portion of which is rotatably supported ona mechanism frame and the other end of which is provided with a contactpoint engagable with a stationary contact in the mechanism. Anintermediate portion of the movable contact arm is operatively connectedto one end of a pair of links operatively connected in series, the otherend of the links being operatively connected to an operating handlerotatably mounted on the mechanism frame. A latching member is rotatablymounted on the mechanism frame, being engageable with one end of areleasable member, the other end of the releasable member beingoperatively connected to a knee connection between the pair of links,whereby the movement of the knee connection is restricted by thereleasable member when latched by the latching member. Thus, the movablecontact arm is actuated by the operating handle when the releasablemember is latched by the latching member, and the movable contact armcan be tripped when the restriction in the movement of the kneeconnection of the links is released due to disengagement of thereleasable member with the latching member as may be caused by therotation thereof.

3 Claims, 5 Drawing Figures PAIENTEUunv 20 m SHEET 10F 2 3 77 NO-FUSECIRCUIT BREAKER BACKGROUND OF THE INVENTION 1. Field of The InventionThis invention relates generally to a no-fuse circuit breaker of arelatively small rated overload current.

2. Description Of The Prior Art Many kinds of mechanisms for use asrelatively small no-fuse circuit breakers have heretofore beendeveloped, but these mechanisms that are adapted for use in combinationwith an electromagnetic trip arrangement, while being generallysuccessful, have had such disadvantages that they have not been found tobe entirely satisfactory. For example, these mechanisms have beenrelatively complicated and therefore difficult to adjust, and inaddition, a high degree of manufacturing accuracy has thus beenrequired.

SUMMARY OF THE INVENTION Accordingly, it is an object of the presentinvention to provide a no-fuse circuit breaker of relatively small sizeand of simple construction.

Another object of this invention is to provide a nofuse circuit breakerwhich is capable of being tripped by a relatively small force.

- Still another object of this invention is to provide an improvedno-fuse circuit breaker, which is adapted for use in combination with anelectro-magnetic trip arrangement.

Briefly stated, the foregoing objects and others are achieved accordingto one aspect of this invention through the provision of a circuitbreaker having a movable contact arm rotatably supported about one endin a mechanism frame and having a contact member on its other endengage-able with a stationary con tact member mounted in the mechanismframe, an operating handle rotatably supported in said mechanism frameand operatively connected through a pair of seri- .member to disengageit from the releasable member responsive to a current larger than apredetermined value in the circuit.

BRIEF DESCRIPTION OF THE DRAWINGS Various other objects, features andattendant advantages of the present invention will be more fullyappreciated as the same becomes better understood from the followingdetailed description when considered in conjunction with theaccompanying drawings wherein like reference numerals designate like orcorresponding parts throughout the several views, and in which:

FIG. 1 isv a schematical side view, shown partially in cross-section, ofa preferred embodiment of the present invention, the mechanism beingshown in the circuit open state;

FIG. 2 is a schematical side view, with parts omitted, of the necessary.portion of the embodiment shown in FIG. 1 forillustrating the operationthereof, the mechanism being shown in the circuit closed state;

FIG. 3 is a view similar to that shown in FIG. 2 wherein the mechanismis shown in the open state just after having been tripped;

FIG. 4 is a perspective view of important portions in the embodimentshown in FIG. 1; and

FIG. 5 is a perspective view, partially broken away and with some partsomitted of a three-pole" no-fuse circuit breaker according to themechanism of the embodiment shown in FIG. 1.

DETAILED DESCRIPTION OF A PREFERRED EMBODIMENT Referring now to thedrawings, and particularly to FIG. 1 thereof, a no-fuse circuit breakeris shown having a casing which comprises a base 11 and a cover 12 ofinsulating material.

A line terminal 13 is provided in the base 11 at one end thereof havingan extension 14 carrying a stationary contact 15. On the other end ofthe base 11 there is provided a load terminal 16 electrically connectedto a coil 17, to be described, which in turn is electrically connectedto a movable contact arm 18 through a flexible conductor 19.

There is provided a mechanism frame 20 comprising a pair of side platemembers 21 and 22 and L-shaped yoke member 23, all of these membersbeing made of metal. The side plates 21 and 22 are symmetrical inconstruction and disposed in parallel planes, as shown in FIG. 4, andare secured to the yoke member 23 by suitable means, such as by a forcefit. (In FIG. l'the side plate 22 is not seen, and in FIGS. 2 and 3 theside plate 21 is omitted.) Arcuate slots 211 and 221 are provided in theside plates 21 and 22, respectively, as shown in FIG. 4.

Rotatably mounted on the top of the frame'20 by a pin 24 is an operatinghandle 25, of conventional design being made of insulating material,which is operatively connected to a link 26 by a pin 27. The handle 25is spring biased in the counter clockwise direction, as viewed in thedrawings, by a pair of spring 28 provided around the pin 24 and outsidethe lower extension of the handle 25 between the side plates 21 and 22,as shown in FIG. 1, only the one spring of the side viewed in thedrawing being shown.

The movable contact arm 18 has an integral projected portion 181 at oneend for functioning as a stop and an egg-shaped hole 182 having a pin 29inserted therein for supporting the arm 18 on the frame 20. The movablecontact arm 18 is provided also with a contact 30 at its other end,being engageable with the stationary contact 15. The idle clearancebetween the hole 182 and the pin 29, by incorporating a spring 31,permits contact pressure to be provided between the movable andstationary contacts 30 and 15. The spring 31 gives a biasing force inthe counter-clockwise direction, as viewed in the drawings, and is ofthe shape shown in FIG. 4. The intermediate portion of the movablecontact arm 18 is operatively connected by an insulated pin 32 to alower link 33 which is rotatably connected, at the top end portionthereof, to the bottom end portion of the upper link 26 to form a kneeconnection.

A releasable member 34 is provided, a lower end thereof being connectedto the knee connection beend of the member 34 is slidable in the slots211 and 221, and is adapted to be latched. Thus, the movement of theknee connecting axis is restricted by the releasable member when thesame is latched. In detail, the releasable member 34 is a U-shaped rodas shown in FIG. 4, one leg portion 341 thereof acting as a connectingpin for links 26 and 33, and the other leg portion 342 being insertedthrough the slots 211 and 221 of the side plates 21 and 22 so as to beslidably guided by the slots 211 and 221.

Latching of the releasable member 34 is provided by a latching member 35rotatably mounted on the mechanism frame by a pin 36. The member 35 hastooth portions 351 and 352 capable of latching the upper leg portion 342of the releasable member 34, and has arms 353 and 354 to support anactuating rod 37 of insulating material, as clearly shown in FIG. 4. Thelatching member 35 is also spring biased in the clockwise direction, asviewed in the drawings, by a spring 38 provided around the pin 36between the arms 353 and 354. An operation to move the rod 37 righward,as seen in FIG. 4, will cause the releasable member 34 to be releasedfrom its engagement with the latching member 35.

In order to actuate the rod 37 in the rightward direction when a currentlarger than a predetermined value flows from the line terminal 13 to theload terminal 16, the coil 17, already mentioned, is arranged in serieswith the current path between the line and load terminals 13 and 16.Mounted in the axial bore of the coil 17 is a core member 39 of softferro-magnetic material, such as soft iron, which is fixed to the yokemember 23 and has a pole portion 391 at the top end thereof. Facing thepole portion is an armature member 40, also of soft ferro-magneticmaterial, such as soft iron, which is rotatably mounted on the mechanismframe 20 by the pin 36 together with the latching member 35, butindependently therefrom. As clearly shown in FIG. 4, the armature 40 hasa pair of extensions 401 and 402, each having a lower portion bent in asubstantially U-shaped configuration the base of which can abut on therod 37 to move the same to the right when the armature 40 rotates aboutthe pin 36 in the counter-clockwise direction. The armature 40 is alsospring biased in the clockwise direction by a compression spring 411provided between a tab 403 of the armature 40 and a tab 231 of the yokemember 23.

A suitable arc extinguishing structure 41 of conventional design isprovided in the base 11. The reference numeral 42 designates aprojection of elongated cubelike shape integrally provided on the innerwall of the cover 12 for limiting the upward movement of the mechanismframe 20.

In operation, in order to close the circuit breaker from the open stateshown in FIG. 1, the operating handle 25 must be moved from the OFF"position to the ON" position. In the OFF" position, which also means theRESET" position, the latched leg portion 342 of the releasable member 34is engaged with the tooth portions 351 and 352 of the latching member35, so that the releasable member 34 is latched by the latching member35, whereby the knee connection of the links 26 and 33 can be moved onlyalong the circular locus as indicated by the reference character A inFIG. 1. Accordingly, the operating handle 25 is operated to rotate inthe clockwise direction, against the biasing force of the springs 28 and31, whereupon the movable contact arm 18 rotates substantially aroundthe pin 29 in the clockwise direction to contact the movable contact 30with the stationary contact 15. In accordance with that movement, theintermediate portion of the contact arm 18 is then moved furtherdownward by the link 33, and the contact arm 18 is rotated in thecounter-clockwise direction substantially around the contact point ofthe contacts 15 and 30 because of the presence of the clearance 182about the pin 29. Thus, the biasing force of the spring 31 functions toprovide suitable contact pressure between the movable and stationarycontacts 30 and 15. When the pin 27 passes substantially over animaginary line defined by connecting the pin 24 and the knee connectionaxis of the links 26 and 33, the upward force in the link 33 caused bythe spring 31 urges the handle 25 to rotate in the clockwise directionagainst the biasing force of the springs 28, but such clockwise rotationof the handle 25 is now limited by the collision of the pin 27 with sideplates 21 and 22, as shown in FIG. 2. Hence the mechanism holds theclosed state of the circuit. In this connection, the latched leg 342 ofthe releasable mem ber 34 will move to the right because it is slidablyguided by the slots 211 and 221 as well as being pulled by the links 26and 33, but the leg 342 still remains latched by the latching member 35.

Manual opening of the circuit is performed by rotating the handle 25 inthe counter-clockwise direction. The movements of each of the parts aresimilar, but in reverse relation, so that the detailed explanationthereof may be omitted.

Next the trip operation which occurs when a current above apredetermined value flows in the circuit will be. described.

In the closed state of the circuit, as shown in FIG. 2, the armature 40is pulled down to contact the pole 391 of the core 39 when the flow ofcurrent in the coil 17 becomes larger than a predetermined value. Themovement of the extensions 401 and 402 of the armature 40 pushes theinsulator rod 37 supported by the arms 353 and 354 of the latchingmember 35 to the right so that the latching member 35 rotates in thecounterclockwise direction to release the latched leg 342 of thereleasable member 34. Accordingly, the upper leg 342 of the releasablemember 34, which was latched until this time, as shown in FIG. 2,becomes movable rightwardly and moves rightward along the slots 211 and221 of the side plates 21 and 22, because the member 34 is pulled by thelinks 26 and 33. In other words, restriction in the movement of the kneeconnection axis ofthe links 26 and 33 is now removed, and the movablecontact 30 becomes separated from the stationary contact 15, as shown inFIG. 3.

Slightly after this, or substantially at the same time, the operatinghandle 25 is caused to rotate in the counter-clockwise direction by thesprings 28. In response to this, the link 26, first moves downwardly andclockwisely, and then moves upwardly and clockwisely, with result thatthe upper leg 342 of the releasable member 34 moves leftwardly along theslots 211 and 221 to be re'engaged by the latching member 35. Thus, whenan overlaod current flows, the mechanism is automatically tripped andreset, as shown in FIG. 1.

As understood from the above description, by a relatively small force,the latching member can be actuated to release the upper latched leg 342of the releasable member 34, because the upper latched leg 342 isslidably guided by means of the slots 211 and 221 in the side plates 21and 22, and the mechanism can be comconstruction except that the rod 37mounted on the latching member 35 and the rod 32 for actuating themovable contact arm 18 extend axially beyond both ends from that shownin FIGS. [-4. Each of the two outside mechanisms has no handle 25 oftheir own, nor the upper and lower links 26 and 33, the releasablemember 34, and the latching member 35. The respecl tive movable contactarms 18 in the two outside mechanisms are connected to the actuating rod32 of the central mechanism, whereby all of the movable contact arms 18are operated simultaneously, and the latching member 35 provided only inthe central mechanism can be moved by operation of at least one of thearmatures 40 provided on the respective poles. Thus, all of the movablecontact arms 18 can be operated manually by the handle 25, and all ofthe circuits can be tripped when an overload current flows in any one ofthe poles.

Obviously many modifications and variations of the present invention arepossible in light of these teachings. it is therefore to be understoodthat within the scope of the appended claims, the invention may bepracticed otherwise than as specifically described herein.

What is claimed as new and desired to be secured by Letters Patent ofthe United States is:

l. A no-fuse circuit breaker comprising:

an insulative casing;

a mechanism frame mounted in said casing at one side thereof and havinga pair of side plates arranged in parallel relation, each of said'sideplates having an elongated slot therein;

a stationary contact member mounted on the other side of said casing atthe bottom thereof;

a movable contact arm supported at one end thereof by and between saidside plates, having a contact portion at the other end thereofengageable with said stationary contact member and being spring biasedto normally separate said contact portion thereof from said stationarycontact member;

an operating handle rotatably supported by and between said side platesand having one portion extending outwardly from said casing;

an upper link rotatably connected at one end portion thereof to saidoperating handle at another portion;

a lower link operatively connected at one end portion thereof to theother end portion of said upper link, the other end portion of saidlower link being rotatably connected to an intermediate portion of saidmovable contact arm;

a releasable member operatively connected at one end portion thereof tothe connection between said upper and lower links, and being slidablyguided at its other end portion by said slots in said side plates;

a latching member rotatably mounted on and between said side plates,being capable of latching said other end portion of said releasablemember, and being spring biased to be resiliently kept in positionengageable with said other end portion of said releasable member; and

means for actuating said latching member to disengage from saidreleasable member in response to a flow of current larger than apredetermined value;

whereby said movable contact arm may be actuated to open and close saidmovable contact portion thereof and said stationary contact by saidoperating handle when said releasable member is latched by said latchingmember, and said movable contact arm can be tripped when the engagementof said releasable member with said latching member is released by theoperation of said actuating means.

2. A no-fuse circuit breaker as claimed in claim 1,

where said releasable member is a substantially U-shaped rod, one legportion thereof being adapted to function as a connecting pin for saidupper and lower links and the other leg portion thereof being insertedthrough said slots in said side plates.

3. A no-fuse circuit breaker as claimed in claim 1,

wherein said means for actuating said latching member is anelectromagnetic trip arrangement.

l l l

1. A no-fuse circuit breaker comprising: an insulative casing; amechanism frame mounted in said casing at one side thereof and having apair of side plates arranged in parallel relation, each of said sideplates having an elongated slot therein; a stationary contact membermounted on the other side of said casing at the bottom thereof; amovable contact arm supported at one end thereof by and between saidside plates, having a contact portion at the other end thereofengageable with said stationary contact member and being spring biasedto normally separate said contact portion thereof from said stationarycontact member; an operating handle rotatably supported by and betweensaid side plates and having one portion extending outwardly from saidcasing; an upper link rotatably connected at one end portion thereof tosaid operating handle at another portion; a lower link operativelyconnected at one end portion thereof to the other end portion of saidupper link, the other end portion of said lower link being rotatablyconnected to an intermediate portion of said movable contact arm; areleasable member operatively connected at one end portion thereof tothe connection between said upper and lower links, and being slidablyguided at its other end portion by said slots in said side plates; alatching member rotatably mounted on and between said side plates, beingcapable of latching said other end portion of said releasable member,and being spring biased to be resiliently kept in position engageablewith said other end portion of said releasable member; and means foractuating said latching member to disengage from said releasable memberin response to a flow of current larger than a predetermined value;whereby said movable contact arm may be actuated to open and close saidmovable contact portion thereof and said stationary contact by saidoperating handle when said releasable member is latched by said latchingmember, and said movable contact arm can be tripped when the engagementof said releasable member with said latching member is released by theoperation of said actuating means.
 2. A no-fuse circuit breaker asclaimed in claim 1, where said releasable member is a substantiallyU-shaped rod, one leg portion thereof being adapted to function as aconnecting pin for said upper and lower links and the other leg portionthereof being inserted through said slots in said side plates.
 3. Ano-fuse circuit breaker as claimed in claim 1, wherein said means foractuating said latching member is an electromagnetic trip arrangement.